NEUTRON REFLECTIVITY OF ADSORBED BETA-CASEIN AND BETA-LACTOGLOBULIN AT THE AIR/WATER INTERFACE

被引:178
作者
ATKINSON, PJ
DICKINSON, E
HORNE, DS
RICHARDSON, RM
机构
[1] HANNAH RES INST, AYR KA6 5HL, SCOTLAND
[2] UNIV BRISTOL, SCH CHEM, BRISTOL BS8 1TS, AVON, ENGLAND
来源
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS | 1995年 / 91卷 / 17期
关键词
D O I
10.1039/ft9959102847
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Adsorption of the pure milk proteins, beta-casein and beta-lactoglobulin, at the air/water interface has been studied using the technique of specular neutron reflectance. By fitting appropriate models of the protein films to the reflectivity data the detailed structures of the interfaces have been determined. The effects of protein concentration, substrate pH, film ageing and the presence of calcium ions on the film structures have been investigated. At neutral pH both beta-casein and beta-lactoglobulin form a monolayer at the air/water boundary that can be divided into a protein-rich, hydrophobic, inner layer closest to the interface, and a more diffuse, hydrophilic, outer layer extending into the bulk aqueous phase. The adsorbed amount of protein follows the adsorption isotherms determined by other methods. Ageing has little effect on beta-casein layers, but with beta-lactoglobulin there is an increase in the adsorbed amount of protein with time and the two-layer model of the film configuration tends to become less distinct such that a one-layer model form is equally appropriate. The rate and extent of the changes occurring as a function of the age of the surface depend on the pH of the substrate solution. The adsorbed amount of both proteins increases as the pH is lowered towards their respective isoelectric points. Models are proposed to account for the changes in layer structure occurring during these processes. The presence of calcium ions modifies the structure of beta-casein layers, reducing the hydrophilic layer thickness and the adsorbed amount of protein.
引用
收藏
页码:2847 / 2854
页数:8
相关论文
共 20 条
  • [1] [Anonymous], 1992, INTRO FOOD COLLOIDS
  • [2] DYNAMIC AND STATIC PROPERTIES OF PROTEINS ADSORBED AT AIR-WATER-INTERFACE
    BENJAMINS, J
    FEIJTER, JAD
    EVANS, MTA
    GRAHAM, DE
    PHILLIPS, MC
    [J]. FARADAY DISCUSSIONS, 1975, 59 : 218 - 229
  • [3] INFLUENCE OF ELECTROSTATIC INTERACTIONS ON BETA-CASEIN LAYERS ADSORBED ON POLYSTYRENE LATICES
    BROOKSBANK, DV
    DAVIDSON, CM
    HORNE, DS
    LEAVER, J
    [J]. JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS, 1993, 89 (18): : 3419 - 3425
  • [4] NEUTRON REFLECTION FROM A LIQUID LIQUID INTERFACE
    COSGROVE, T
    PHIPPS, JS
    RICHARDSON, RM
    [J]. COLLOIDS AND SURFACES, 1992, 62 (03): : 199 - 206
  • [5] DALGLEISH DG, 1990, COLLOID SURFACE, V65, P9
  • [6] A NEUTRON REFLECTIVITY STUDY OF THE ADSORPTION OF BETA-CASEIN AT FLUID INTERFACES
    DICKINSON, E
    HORNE, DS
    PHIPPS, JS
    RICHARDSON, RM
    [J]. LANGMUIR, 1993, 9 (01) : 242 - 248
  • [7] CALCIUM INDUCED FLOCCULATION OF EMULSIONS CONTAINING ADSORBED BETA-CASEIN OR PHOSVITIN
    DICKINSON, E
    HUNT, JA
    HORNE, DS
    [J]. FOOD HYDROCOLLOIDS, 1992, 6 (04) : 359 - 370
  • [8] NEUTRON REFLECTIVITY STUDY OF THE COMPETITIVE ADSORPTION OF BETA-CASEIN AND WATER-SOLUBLE SURFACTANT AT THE PLANAR AIR-WATER-INTERFACE
    DICKINSON, E
    HORNE, DS
    RICHARDSON, RM
    [J]. FOOD HYDROCOLLOIDS, 1993, 7 (06) : 497 - 505
  • [9] FOOD COLLOIDS - AN OVERVIEW
    DICKINSON, E
    [J]. COLLOIDS AND SURFACES, 1989, 42 (1-2): : 191 - 204
  • [10] A NEUTRON REFLECTIVITY STUDY OF A SPREAD MONOLAYER OF BOVINE SERUM-ALBUMIN
    EAGLESHAM, A
    HERRINGTON, TM
    PENFOLD, J
    [J]. COLLOIDS AND SURFACES, 1992, 65 (01): : 9 - 16